<?php
/**
* The MIT License

Copyright (c) 2007 Andy Smith

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.


http://oauth.googlecode.com/
http://www.apache.org/licenses/LICENSE-2.0
*/
// vim: foldmethod=marker

/* Generic exception class
 */
class OAuthException extends Exception {/*{{{*/
  // pass
}/*}}}*/

class OAuthConsumer {/*{{{*/
  public $key;
  public $secret;

  function __construct($key, $secret, $callback_url=NULL) {/*{{{*/
    $this->key = $key;
    $this->secret = $secret;
    $this->callback_url = $callback_url;
  }/*}}}*/

  function __toString() {/*{{{*/
    return "OAuthConsumer[key=$this->key,secret=$this->secret]";
  }/*}}}*/
}/*}}}*/

class OAuthToken {/*{{{*/
  // access tokens and request tokens
  public $key;
  public $secret;

  /**
   * key = the token
   * secret = the token secret
   */
  function __construct($key, $secret) {/*{{{*/
    $this->key = $key;
    $this->secret = $secret;
  }/*}}}*/

  /**
   * generates the basic string serialization of a token that a server
   * would respond to request_token and access_token calls with
   */
  function to_string() {/*{{{*/
    return "oauth_token=" . OAuthUtil::urlencodeRFC3986($this->key) . 
        "&oauth_token_secret=" . OAuthUtil::urlencodeRFC3986($this->secret);
  }/*}}}*/

  function __toString() {/*{{{*/
    return $this->to_string();
  }/*}}}*/
}/*}}}*/

class OAuthSignatureMethod {/*{{{*/
  public function check_signature(&$request, $consumer, $token, $signature) {
    $built = $this->build_signature($request, $consumer, $token);
    return $built == $signature;
  }
}/*}}}*/

class OAuthSignatureMethod_HMAC_SHA1 extends OAuthSignatureMethod {/*{{{*/
  function get_name() {/*{{{*/
    return "HMAC-SHA1";
  }/*}}}*/

  public function build_signature($request, $consumer, $token) {/*{{{*/
    $base_string = $request->get_signature_base_string();
    $request->base_string = $base_string;

    $key_parts = array(
      $consumer->secret,
      ($token) ? $token->secret : ""
    );

    $key_parts = array_map(array('OAuthUtil','urlencodeRFC3986'), $key_parts);
    $key = implode('&', $key_parts);

    return base64_encode( hash_hmac('sha1', $base_string, $key, true));
  }/*}}}*/
}/*}}}*/

class OAuthSignatureMethod_PLAINTEXT extends OAuthSignatureMethod {/*{{{*/
  public function get_name() {/*{{{*/
    return "PLAINTEXT";
  }/*}}}*/

  public function build_signature($request, $consumer, $token) {/*{{{*/
    $sig = array(
      OAuthUtil::urlencodeRFC3986($consumer->secret)
    );

    if ($token) {
      array_push($sig, OAuthUtil::urlencodeRFC3986($token->secret));
    } else {
      array_push($sig, '');
    }

    $raw = implode("&", $sig);
    // for debug purposes
    $request->base_string = $raw;

    return OAuthUtil::urlencodeRFC3986($raw);
  }/*}}}*/
}/*}}}*/

class OAuthSignatureMethod_RSA_SHA1 extends OAuthSignatureMethod {/*{{{*/
  public function get_name() {/*{{{*/
    return "RSA-SHA1";
  }/*}}}*/

  protected function fetch_public_cert(&$request) {/*{{{*/
    // not implemented yet, ideas are:
    // (1) do a lookup in a table of trusted certs keyed off of consumer
    // (2) fetch via http using a url provided by the requester
    // (3) some sort of specific discovery code based on request
    //
    // either way should return a string representation of the certificate
    throw Exception("fetch_public_cert not implemented");
  }/*}}}*/

  protected function fetch_private_cert(&$request) {/*{{{*/
    // not implemented yet, ideas are:
    // (1) do a lookup in a table of trusted certs keyed off of consumer
    //
    // either way should return a string representation of the certificate
    throw Exception("fetch_private_cert not implemented");
  }/*}}}*/

  public function build_signature(&$request, $consumer, $token) {/*{{{*/
    $base_string = $request->get_signature_base_string();
    $request->base_string = $base_string;
  
    // Fetch the private key cert based on the request
    $cert = $this->fetch_private_cert($request);

    // Pull the private key ID from the certificate
    $privatekeyid = openssl_get_privatekey($cert);

    // Sign using the key
    $ok = openssl_sign($base_string, $signature, $privatekeyid);   

    // Release the key resource
    openssl_free_key($privatekeyid);
  
    return base64_encode($signature);
  } /*}}}*/

  public function check_signature(&$request, $consumer, $token, $signature) {/*{{{*/
    $decoded_sig = base64_decode($signature);

    $base_string = $request->get_signature_base_string();
  
    // Fetch the public key cert based on the request
    $cert = $this->fetch_public_cert($request);

    // Pull the public key ID from the certificate
    $publickeyid = openssl_get_publickey($cert);

    // Check the computed signature against the one passed in the query
    $ok = openssl_verify($base_string, $decoded_sig, $publickeyid);   

    // Release the key resource
    openssl_free_key($publickeyid);
  
    return $ok == 1;
  } /*}}}*/
}/*}}}*/

class OAuthRequest {/*{{{*/
  private $parameters;
  private $http_method;
  private $http_url;
  // for debug purposes
  public $base_string;
  public static $version = '1.0';

  function __construct($http_method, $http_url, $parameters=NULL) {/*{{{*/
    @$parameters or $parameters = array();
    $this->parameters = $parameters;
    $this->http_method = $http_method;
    $this->http_url = $http_url;
  }/*}}}*/


  /**
   * attempt to build up a request from what was passed to the server
   */
  public static function from_request($http_method=NULL, $http_url=NULL, $parameters=NULL) {/*{{{*/
    $scheme = (!isset($_SERVER['HTTPS']) || $_SERVER['HTTPS'] != "on") ? 'http' : 'https';
    @$http_url or $http_url = $scheme . '://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
    @$http_method or $http_method = $_SERVER['REQUEST_METHOD'];
    
    $request_headers = OAuthRequest::get_headers();

    // let the library user override things however they'd like, if they know
    // which parameters to use then go for it, for example XMLRPC might want to
    // do this
    if ($parameters) {
      $req = new OAuthRequest($http_method, $http_url, $parameters);
    } else {
      // collect request parameters from query string (GET) and post-data (POST) if appropriate (note: POST vars have priority)
      $req_parameters = $_GET;
      if ($http_method == "POST" && @$request_headers["Content-Type"] == "application/x-www-form-urlencoded") {
        $req_parameters = array_merge($req_parameters, $_POST);
      }

      // next check for the auth header, we need to do some extra stuff
      // if that is the case, namely suck in the parameters from GET or POST
      // so that we can include them in the signature
      if (@substr($request_headers['Authorization'], 0, 6) == "OAuth ") {
        $header_parameters = OAuthRequest::split_header($request_headers['Authorization']);
        $parameters = array_merge($req_parameters, $header_parameters);
        $req = new OAuthRequest($http_method, $http_url, $parameters);
      } else $req = new OAuthRequest($http_method, $http_url, $req_parameters);
    }

    return $req;
  }/*}}}*/

  /**
   * pretty much a helper function to set up the request
   */
  public static function from_consumer_and_token($consumer, $token, $http_method, $http_url, $parameters=NULL) {/*{{{*/
    @$parameters or $parameters = array();
    $defaults = array("oauth_version" => OAuthRequest::$version,
                      "oauth_nonce" => OAuthRequest::generate_nonce(),
                      "oauth_timestamp" => OAuthRequest::generate_timestamp(),
                      "oauth_consumer_key" => $consumer->key);
    $parameters = array_merge($defaults, $parameters);

    if ($token) {
      $parameters['oauth_token'] = $token->key;
    }
    return new OAuthRequest($http_method, $http_url, $parameters);
  }/*}}}*/

  public function set_parameter($name, $value) {/*{{{*/
    $this->parameters[$name] = $value;
  }/*}}}*/

  public function get_parameter($name) {/*{{{*/
    return isset($this->parameters[$name]) ? $this->parameters[$name] : null;
  }/*}}}*/

  public function get_parameters() {/*{{{*/
    return $this->parameters;
  }/*}}}*/

  /**
   * Returns the normalized parameters of the request
   * 
   * This will be all (except oauth_signature) parameters,
   * sorted first by key, and if duplicate keys, then by
   * value.
   *
   * The returned string will be all the key=value pairs
   * concated by &.
   * 
   * @return string
   */
  public function get_signable_parameters() {/*{{{*/
    // Grab all parameters
    $params = $this->parameters;
		
    // Remove oauth_signature if present
    if (isset($params['oauth_signature'])) {
      unset($params['oauth_signature']);
    }
		
    // Urlencode both keys and values
    $keys = array_map(array('OAuthUtil', 'urlencodeRFC3986'), array_keys($params));
    $values = array_map(array('OAuthUtil', 'urlencodeRFC3986'), array_values($params));
    $params = array_combine($keys, $values);

    // Sort by keys (natsort)
    uksort($params, 'strnatcmp');

    // Generate key=value pairs
    $pairs = array();
    foreach ($params as $key=>$value ) {
      if (is_array($value)) {
        // If the value is an array, it's because there are multiple 
        // with the same key, sort them, then add all the pairs
        natsort($value);
        foreach ($value as $v2) {
          $pairs[] = $key . '=' . $v2;
        }
      } else {
        $pairs[] = $key . '=' . $value;
      }
    }
		
    // Return the pairs, concated with &
    return implode('&', $pairs);
  }/*}}}*/

  /**
   * Returns the base string of this request
   *
   * The base string defined as the method, the url
   * and the parameters (normalized), each urlencoded
   * and the concated with &.
   */
  public function get_signature_base_string() {/*{{{*/
    $parts = array(
      $this->get_normalized_http_method(),
      $this->get_normalized_http_url(),
      $this->get_signable_parameters()
    );

    $parts = array_map(array('OAuthUtil', 'urlencodeRFC3986'), $parts);

    return implode('&', $parts);
  }/*}}}*/

  /**
   * just uppercases the http method
   */
  public function get_normalized_http_method() {/*{{{*/
    return strtoupper($this->http_method);
  }/*}}}*/

  /**
   * parses the url and rebuilds it to be
   * scheme://host/path
   */
  public function get_normalized_http_url() {/*{{{*/
    $parts = parse_url($this->http_url);

    $port = @$parts['port'];
    $scheme = $parts['scheme'];
    $host = $parts['host'];
    $path = @$parts['path'];

    $port or $port = ($scheme == 'https') ? '443' : '80';

    if (($scheme == 'https' && $port != '443')
        || ($scheme == 'http' && $port != '80')) {
      $host = "$host:$port";
    }
    return "$scheme://$host$path";
  }/*}}}*/

  /**
   * builds a url usable for a GET request
   */
  public function to_url() {/*{{{*/
    $out = $this->get_normalized_http_url() . "?";
    $out .= $this->to_postdata();
    return $out;
  }/*}}}*/

  /**
   * builds the data one would send in a POST request
   */
  public function to_postdata() {/*{{{*/
    $total = array();
    foreach ($this->parameters as $k => $v) {
      $total[] = OAuthUtil::urlencodeRFC3986($k) . "=" . OAuthUtil::urlencodeRFC3986($v);
    }
    $out = implode("&", $total);
    return $out;
  }/*}}}*/

  /**
   * builds the Authorization: header
   */
  public function to_header() {/*{{{*/
    $out ='Authorization: OAuth realm=""';
    $total = array();
    foreach ($this->parameters as $k => $v) {
      if (substr($k, 0, 5) != "oauth") continue;
      $out .= ',' . OAuthUtil::urlencodeRFC3986($k) . '="' . OAuthUtil::urlencodeRFC3986($v) . '"';
    }
    return $out;
  }/*}}}*/

  public function __toString() {/*{{{*/
    return $this->to_url();
  }/*}}}*/


  public function sign_request($signature_method, $consumer, $token) {/*{{{*/
    $this->set_parameter("oauth_signature_method", $signature_method->get_name());
    $signature = $this->build_signature($signature_method, $consumer, $token);
    $this->set_parameter("oauth_signature", $signature);
  }/*}}}*/

  public function build_signature($signature_method, $consumer, $token) {/*{{{*/
    $signature = $signature_method->build_signature($this, $consumer, $token);
    return $signature;
  }/*}}}*/

  /**
   * util function: current timestamp
   */
  private static function generate_timestamp() {/*{{{*/
    return time();
  }/*}}}*/

  /**
   * util function: current nonce
   */
  private static function generate_nonce() {/*{{{*/
    $mt = microtime();
    $rand = mt_rand();

    return md5($mt . $rand); // md5s look nicer than numbers
  }/*}}}*/

  /**
   * util function for turning the Authorization: header into
   * parameters, has to do some unescaping
   */
  private static function split_header($header) {/*{{{*/
    // this should be a regex
    // error cases: commas in parameter values
    $parts = explode(",", substr($header, 6)); // skip past "OAuth " at beginning of Authorization header value
    $out = array();
    foreach ($parts as $param) {
      $param = ltrim($param);
      if (strpos($param, "realm=") === 0) continue; // exclude realm param, per section 9.1.1, bullet 1

      $param_parts = explode("=", $param);

      // rawurldecode() used because urldecode() will turn a "+" in the
      // value into a space
      $out[$param_parts[0]] = rawurldecode(substr($param_parts[1], 1, -1));
    }
    return $out;
  }/*}}}*/

  /**
   * helper to try to sort out headers for people who aren't running apache
   */
  private static function get_headers() {/*{{{*/
    if (function_exists('apache_request_headers')) {
      // we need this to get the actual Authorization: header
      // because apache tends to tell us it doesn't exist
      return apache_request_headers();
    }
    // otherwise we don't have apache and are just going to have to hope
    // that $_SERVER actually contains what we need
    $out = array();
    foreach ($_SERVER as $key => $value) {
      if (substr($key, 0, 5) == "HTTP_") {
        // this is chaos, basically it is just there to capitalize the first
        // letter of every word that is not an initial HTTP and strip HTTP
        // code from przemek
        $key = str_replace(" ", "-", ucwords(strtolower(str_replace("_", " ", substr($key, 5)))));
        $out[$key] = $value;
      }
    }
    return $out;
  }/*}}}*/
}/*}}}*/

class OAuthServer {/*{{{*/
  protected $timestamp_threshold = 300; // in seconds, five minutes
  protected $version = 1.0;             // hi blaine
  protected $signature_methods = array();

  protected $data_store;

  function __construct($data_store) {/*{{{*/
    $this->data_store = $data_store;
  }/*}}}*/

  public function add_signature_method($signature_method) {/*{{{*/
    $this->signature_methods[$signature_method->get_name()] = 
        $signature_method;
  }/*}}}*/
  
  // high level functions

  /**
   * process a request_token request
   * returns the request token on success
   */
  public function fetch_request_token(&$request) {/*{{{*/
    $this->get_version($request);

    $consumer = $this->get_consumer($request);

    // no token required for the initial token request
    $token = NULL;

    $this->check_signature($request, $consumer, $token);

    $new_token = $this->data_store->new_request_token($consumer);

    return $new_token;
  }/*}}}*/

  /**
   * process an access_token request
   * returns the access token on success
   */
  public function fetch_access_token(&$request) {/*{{{*/
    $this->get_version($request);

    $consumer = $this->get_consumer($request);

    // requires authorized request token
    $token = $this->get_token($request, $consumer, "request");

    $this->check_signature($request, $consumer, $token);

    $new_token = $this->data_store->new_access_token($token, $consumer);

    return $new_token;
  }/*}}}*/

  /**
   * verify an api call, checks all the parameters
   */
  public function verify_request(&$request) {/*{{{*/
    $this->get_version($request);
    $consumer = $this->get_consumer($request);
    $token = $this->get_token($request, $consumer, "access");
    $this->check_signature($request, $consumer, $token);
    return array($consumer, $token);
  }/*}}}*/

  // Internals from here
  /**
   * version 1
   */
  private function get_version(&$request) {/*{{{*/
    $version = $request->get_parameter("oauth_version");
    if (!$version) {
      $version = 1.0;
    }
    if ($version && $version != $this->version) {
      throw new OAuthException("OAuth version '$version' not supported");
    }
    return $version;
  }/*}}}*/

  /**
   * figure out the signature with some defaults
   */
  private function get_signature_method(&$request) {/*{{{*/
    $signature_method =  
        @$request->get_parameter("oauth_signature_method");
    if (!$signature_method) {
      $signature_method = "PLAINTEXT";
    }
    if (!in_array($signature_method, 
                  array_keys($this->signature_methods))) {
      throw new OAuthException(
        "Signature method '$signature_method' not supported try one of the following: " . implode(", ", array_keys($this->signature_methods))
      );      
    }
    return $this->signature_methods[$signature_method];
  }/*}}}*/

  /**
   * try to find the consumer for the provided request's consumer key
   */
  private function get_consumer(&$request) {/*{{{*/
    $consumer_key = @$request->get_parameter("oauth_consumer_key");
    if (!$consumer_key) {
      throw new OAuthException("Invalid consumer key");
    }

    $consumer = $this->data_store->lookup_consumer($consumer_key);
    if (!$consumer) {
      throw new OAuthException("Invalid consumer");
    }

    return $consumer;
  }/*}}}*/

  /**
   * try to find the token for the provided request's token key
   */
  private function get_token(&$request, $consumer, $token_type="access") {/*{{{*/
    $token_field = @$request->get_parameter('oauth_token');
    $token = $this->data_store->lookup_token(
      $consumer, $token_type, $token_field
    );
    if (!$token) {
      throw new OAuthException("Invalid $token_type token: $token_field");
    }
    return $token;
  }/*}}}*/

  /**
   * all-in-one function to check the signature on a request
   * should guess the signature method appropriately
   */
  private function check_signature(&$request, $consumer, $token) {/*{{{*/
    // this should probably be in a different method
    $timestamp = @$request->get_parameter('oauth_timestamp');
    $nonce = @$request->get_parameter('oauth_nonce');

    $this->check_timestamp($timestamp);
    $this->check_nonce($consumer, $token, $nonce, $timestamp);

    $signature_method = $this->get_signature_method($request);

    $signature = $request->get_parameter('oauth_signature');    
    $valid_sig = $signature_method->check_signature(
      $request, 
      $consumer, 
      $token, 
      $signature
    );

    if (!$valid_sig) {
      throw new OAuthException("Invalid signature");
    }
  }/*}}}*/

  /**
   * check that the timestamp is new enough
   */
  private function check_timestamp($timestamp) {/*{{{*/
    // verify that timestamp is recentish
    $now = time();
    if ($now - $timestamp > $this->timestamp_threshold) {
      throw new OAuthException("Expired timestamp, yours $timestamp, ours $now");
    }
  }/*}}}*/

  /**
   * check that the nonce is not repeated
   */
  private function check_nonce($consumer, $token, $nonce, $timestamp) {/*{{{*/
    // verify that the nonce is uniqueish
    $found = $this->data_store->lookup_nonce($consumer, $token, $nonce, $timestamp);
    if ($found) {
      throw new OAuthException("Nonce already used: $nonce");
    }
  }/*}}}*/



}/*}}}*/

class OAuthDataStore {/*{{{*/
  function lookup_consumer($consumer_key) {/*{{{*/
    // implement me
  }/*}}}*/

  function lookup_token($consumer, $token_type, $token) {/*{{{*/
    // implement me
  }/*}}}*/

  function lookup_nonce($consumer, $token, $nonce, $timestamp) {/*{{{*/
    // implement me
  }/*}}}*/

  function fetch_request_token($consumer) {/*{{{*/
    // return a new token attached to this consumer
  }/*}}}*/

  function fetch_access_token($token, $consumer) {/*{{{*/
    // return a new access token attached to this consumer
    // for the user associated with this token if the request token
    // is authorized
    // should also invalidate the request token
  }/*}}}*/

}/*}}}*/


/*  A very naive dbm-based oauth storage
 */
class SimpleOAuthDataStore extends OAuthDataStore {/*{{{*/
  private $dbh;

  function __construct($path = "oauth.gdbm") {/*{{{*/
    $this->dbh = dba_popen($path, 'c', 'gdbm');
  }/*}}}*/

  function __destruct() {/*{{{*/
    dba_close($this->dbh);
  }/*}}}*/

  function lookup_consumer($consumer_key) {/*{{{*/
    $rv = dba_fetch("consumer_$consumer_key", $this->dbh);
    if ($rv === FALSE) {
      return NULL;
    }
    $obj = unserialize($rv);
    if (!($obj instanceof OAuthConsumer)) {
      return NULL;
    }
    return $obj;
  }/*}}}*/

  function lookup_token($consumer, $token_type, $token) {/*{{{*/
    $rv = dba_fetch("${token_type}_${token}", $this->dbh);
    if ($rv === FALSE) {
      return NULL;
    }
    $obj = unserialize($rv);
    if (!($obj instanceof OAuthToken)) {
      return NULL;
    }
    return $obj;
  }/*}}}*/

  function lookup_nonce($consumer, $token, $nonce, $timestamp) {/*{{{*/
    if (dba_exists("nonce_$nonce", $this->dbh)) {
      return TRUE;
    } else {
      dba_insert("nonce_$nonce", "1", $this->dbh);
      return FALSE;
    }
  }/*}}}*/

  function new_token($consumer, $type="request") {/*{{{*/
    $key = md5(time());
    $secret = time() + time();
    $token = new OAuthToken($key, md5(md5($secret)));
    if (!dba_insert("${type}_$key", serialize($token), $this->dbh)) {
      throw new OAuthException("doooom!");
    }
    return $token;
  }/*}}}*/

  function new_request_token($consumer) {/*{{{*/
    return $this->new_token($consumer, "request");
  }/*}}}*/

  function new_access_token($token, $consumer) {/*{{{*/

    $token = $this->new_token($consumer, 'access');
    dba_delete("request_" . $token->key, $this->dbh);
    return $token;
  }/*}}}*/
}/*}}}*/

class OAuthUtil {/*{{{*/
  public static function urlencodeRFC3986($string) {/*{{{*/
    return str_replace('+', ' ',
                       str_replace('%7E', '~', rawurlencode($string)));
    
  }/*}}}*/
    

  // This decode function isn't taking into consideration the above 
  // modifications to the encoding process. However, this method doesn't 
  // seem to be used anywhere so leaving it as is.
  public static function urldecodeRFC3986($string) {/*{{{*/
    return rawurldecode($string);
  }/*}}}*/
}/*}}}*/

